In the field of packet-switched networks, service providers may often have peering relationships with other service providers. Peering relationships provide interconnectivity between the networks of the service providers and allow the customers of peering networks to connect. Peering is typically accomplished at established physical locations or exchange points using peered border elements, through which data may be exchanged between the networks. Two service providers with a peering relationship may maintain multiple exchange points to accommodate large services areas and reduce the distances packet data must travel to reach a destination. For example, two service providers in the United States may maintain exchange points in New York, Chicago, Houston and Los Angeles. Further, each exchange point may feature multiple peered border elements between a given pair of service providers.
Quality-of-Service (QoS), when used in communications, refers to resource reservation control. Implementing QoS may provide different priority levels to different users according to, for example, a customer service contract or an application type. QoS may also guarantee a certain level of performance to a data flow, which can be important when network capacity is limited (i.e., network congestion). Certain applications, such as Voice over Internet Protocol (VoIP), require a certain guarantee of availability and maximum packet delay, which may be provided by a QoS guarantee, to function properly.